This invention relates to vascular prostheses of improved biocompatability and more specifically to stents in combination with a collagen material. Such a combination provides an endovascular stent which protects the vascular wall and forms a non-thrombogenic cushion for the stent in the vascular lumen.
It also relates to stents in combination with a collagen liner material. Such a combination provides an endoluminal stent which engages the luminal wall and in the case of vascular applications, forms a non-thrombogenic surface as well as providing for the growth of endothelial cells, as well as a reservoir or point of attachment for therapeutic agents in any application.
It also relates to combinations of both of the foregoing arrangements.
Broadly, it relates to stents associated with an outer covering of collagen material and/or a luminal liner of same. It also relates to a method of applying collagen to the interior of a vessel or the like as a liner by using a stent.
Stents are generally tubular in configuration, are open ended, and are radially expandable between a generally unexpanded insertion diameter and an expanded implantation diameter which is greater than the unexpanded insertion diameter. Such intravascular implants are used for maintaining vascular patency in humans and animals.
Stents are typically placed or implanted by a mechanical transluminal procedure. One common procedure for implanting a stent is to first open the region of the vessels with a balloon catheter and then place the stent in a position that bridges the treated portion of the vessel by means of a placement catheter.
Prior art patents refer to the construction and design of stents as well as apparatus for positioning stents within a vessel. In general, for example, such patents disclose a technique for positioning an elongated cylindrical stent at a region of an aneurysm, stenosis or the like. The stent expands as necessary to an implanted configuration after insertion with the aid of a catheter.
Specifically, U.S. Pat. No. 4,733,665 to Palmaz which issued Mar. 29, 1988, discloses a number of stent configurations for implantation with the aid of a catheter. The catheter includes means for mounting and retaining the stent, preferably on an inflatable portion of the catheter. The stent is implanted by positioning it within the blood vessel and monitoring its position on a viewing monitor. Once the stent is properly positioned, the catheter is expanded and the stent separated from the catheter body. The catheter can then be withdrawn from the subject, leaving the stent in place within the blood vessel. U.S. Pat. No. 4,950,227 to Savin et al., which issued on Aug. 21, 1990 is similar.
Another similar U.S. Pat. No. 5,019,090 discloses a generally cylindrical stent and a technique for implanting it using a deflated balloon catheter to position the stent within a vessel. Once the stent is properly positioned the balloon is inflated to press the stent against the inner wall linings of the vessel. The balloon is then deflated and withdrawn from the vessel, leaving the stent in place.
A patent to Dotter, U.S. Pat. No. 4,503,569 which issued Mar. 12, 1985 discloses a spring stent which expands to an implanted configuration with a change in temperature. The spring stent is implanted in a coiled orientation and heated to cause the spring to expand due to the characteristics of the shape memory alloy from which the stent is made. Similarly, U.S. Pat. No. 4,512,338 to Balko et al., which issued Apr. 23, 1985, discloses a shape memory alloy stent and method for its delivery and use other kinds of self-expanding stents are known in the art.
The delivery and expansion of the stent of the invention is the same as that already known in the art and practiced with the stent of FIGS. 1 and 6. U.S. Pat. No. 5,195,984 to Schatz, issued Mar. 23, 1993, describes a typical balloon expansion procedure for an expandable stent. This patent is incorporated in its entirety herein by reference. That patent describes a catheter having an expandable inflatable portion associated therewith. In a conventional manner, the catheter and stent are delivered to a desired location within a body passageway at which it is desired to expand the stent for implantation. Fluoroscopy, and or other conventional techniques may be utilized to insure that the catheter and graft are delivered to the desired location. The stent is then controllably expanded and deformed by controllably expanding the expandable inflatable portion of catheter, typically a balloon. As a result the stent is deformed radially outwardly into contact with the walls of the body passageway. In this regard, the expandable inflatable portion of the catheter may be a conventional angioplasty balloon as is already known in the art. After the desired expansion and deformation of the stent has been accomplished, the angioplasty balloon may be deflated and the catheter removed in a conventional manner from the passageway.
Also, this invention is useful in self-expanding stents such as those disclosed in U.S. Pat. Nos. 4,732,152 and 4,848,343, both of which are incorporated herein by reference.
All of the above-identified patents are incorporated herein by reference.
In one preferred form a metal or other stent is delivered for vascular implantation with a covering sleeve of collagen material. If the stent is of the variable diameter type, the sleeve may be stretched into place or otherwise positioned between the stent and the vascular wall when the stent is seated or deployed. A drug or other agent such as heparin or the like may be included in the collagen for release after stent deployment.
In another preferred form a metal or other stent is delivered for vascular implantation with a luminal liner of collagen material. A drug or other agent such as heparin or the like may be included in the collagen as a surface treatment or for release after stent deployment.
In yet another preferred form, a stent is provided with both an inner collagen liner and outer collagen coating.